1. Field of the Invention
The present invention relates to a display device and an output buffer circuit, and more particularly to a display device using light emitting elements in pixels, respectively, and an output buffer circuit for driving the same.
2. Description of the Related Art
In recent years, a planar self-emission type display device using organic Electroluminescence (EL) elements as light emitting elements has been actively developed. Since the organic EL element emits a light when an electric field is applied across an organic thin film, and has superior visibility although it is driven with a low voltage, the organic EL element is expected as contributing to the weight-lightening, the film thinning, and the low power consumption of the display device.
In the display device using the organic EL elements, an electric field which is applied across the organic thin film is controlled by a drive transistor composing a pixel circuit. However, a threshold voltage and a mobility which the drive transistor has disperse every drive transistor. For this reason, it is necessary to execute processing for correcting differences in threshold voltage and mobility between each two drive transistors. Heretofore, the pixel circuit adapted to execute such correction processing is unsuitable for the high definition promotion in the display device due to complication of a manufacture process, and reduction of an aperture ratio because a large number of constituent elements are required. On the other hand, there is proposed a display device in which a signal intended to be supplied to a pixel circuit is switched, thereby simplifying a configuration of the pixel circuit. This display device, for example, is disclosed in Japanese Patent Laid-Open No. 2007-310311 (refer to FIG. 3A). Specifically, in a state in which a potential at a High (H) level is applied from a power source line to a drive transistor, a reference signal is supplied from a data line to a pixel circuit, thereby carrying out threshold voltage correction. After that, a data signal on the data line is switched from the reference signal over to a video signal, and the video signal is supplied to the pixel circuit, thereby carrying out mobility correction. In addition thereto, after a light emitting element is caused to emit a light, the potential of the power source line is switched from the H level over to a Low (L) level, thereby initializing the drive transistor. In such a manner, one signal is switched over to another different one for the data line and the power source line, and another different signal is supplied to the drive signal, thereby making it possible to simplify the configuration of the pixel circuit.